An organic EL display panel of an organic EL display device mounted on a portable telephone set, a PHS, a DVD player or a PDA (portable terminal device) having 396 (132×3) terminal pins of column line and 162 row line terminal pins has been proposed and the number of terminal pins of the column line and the number of terminal pins of row line tend to be further increased.
A current drive circuit of such organic EL display panel includes output stage current sources such as current mirror circuits provided correspondingly to terminal pins regardless of the type, the active matrix type or the passive matrix type.
In the passive matrix type organic EL display panel, organic EL elements (referred to as “OEL” element, hereinafter) are directly driven by the current sources. In the active matrix type organic EL display panel, pixel circuits each constructed with a capacitor, a current drive transistor and an OEL element are provided in a matrix correspondingly to display cells (pixels). The OEL element is current-driven by a drive transistor correspondingly to a voltage value stored in the capacitor, which is charged by a current corresponding to a drive current from the output stage current source.
An example of a current drive circuit of such organic EL display panel, in which a D/A converter circuit is provided for each column pin, is disclosed in JP2002-234655A (Patent Reference 1) of the applicant of this application. In this example, the D/A converters corresponding to the column pins generate drive currents in column direction corresponding to the column pins by D/A-converting display data according to a reference drive current or a current, on which the drive currents are generated, and output stage current sources of current mirror circuits are driven by the thus generated drive currents.
Patent Reference 1: JP2003-288051A